“The pencil is a very perfect object,” says pencil obsessed Caroline Weaver in this TED video where she explains the history of the pencil.

The origin of the pencil goes back to the innovative applications of graphite. Farmers and shepherds used graphite sticks wrapped in sheepskin and paper to mark their animals.

In 1795, French painter Nicolas-Jacques Conté grounded graphite, mixed it with clay and water to make a paste that was then burned in a kiln to be inserted two cylinders of wood. This is the same method for making pencils we still use to this day!

The #2 Pencil

In the mid-American philosopher, Henry David Thoreau came up with the graphite grading scale for hardness in pencils, most notably the number 2 pencil. Number 2 pencils were thought to be the perfect balance of graphite and color. Conversely, Number 4 pencils were firmer — they contained more clay and thus wrote finer lines.

Years later, America’s Joseph Dixon is widely credited for using machines to produce the first standard hexagonal-shaped pencils.

The Attached Eraser and Yellow Pencil

Before the eraser, people used bread crumbs and rubber to get rid of marks. In 1858, American stationer Hymen Lipman patented the first pencil with an attached eraser. In 1889, the World’s Fair in Paris introduced the first yellow pencil called the Koh-I-Noor which had 14 coats of yellow paint with the end dipped in 14ct gold. Showing off the original plain wood grains quickly went out of style the iconic yellow pencil we know today was born.

If you want to understand a complicated device like a brain, you should build one…The brain’s a big neural network.

Geoff Hinton has been trying to make computers think like humans for over 40 years. In our time, before our time, Hinton the pariah kept pushing the idea that computers could think. The 21st-century rise of the internet and machine learning vindicate his work.

Sometimes spiders ride the wind. They spin out lines of silk that are caught by the breeze and carry them aloft. They have been reported to rise a mile or two above the earth, and perhaps even to cross oceans.

It’s called ballooning.

Watch the spider raise the leg to test the wind and then shoot silk up to six feet long to ride through the air.

According to Harvard psychologist Shawn Achor’s book The Happiness Advantage, it is happiness that begets success and not the other way around.

And one of the quickest ways to boost your mood is to start by sending someone a quick email every morning.

The simplest thing you can do is a two-minute email praising or thanking one person that you know. We’ve done this at Facebook, at US Foods, we’ve done this at Microsoft. We had them write a two-minute email praising or thanking one person they know, and a different person each day for 21 days in a row. That’s it. What we find is this dramatically increases their social connection which is the greatest predictor of happiness we have in organizations. It also improves teamwork. We’ve measured the collective IQ of teams and the collective years of experience of teams but both of those metrics are trumped by social cohesion.

For a longer-term impact on happiness, Achor advises checking your attitude, sociability, and how you choose to view challenges.

That’s right, in this clip Paul McCartney looks old. Nearly frail. It’s still him, but he’s a grandpa. Hip, but a bit crotchety when it comes to movement. And you’re not turned off in the least, you want to will him to go on, to never die, to be here forever, because once he’s gone, we’re next.